docs: def smsc(self):
          """ :return: The default SMSC number stored on the SIM card """
          if self._smscNumber == None:
              try:
                  readSmsc = self.write('AT+CSCA?')
              except SmscNumberUnknownError:
                  pass # Some modems return a CMS 330 error if the value isn't set
              else:
                  cscaMatch = lineMatching(r'\+CSCA:\s*"([^,]+)",(\d+)$', readSmsc)
                  if cscaMatch:
                      self._smscNumber = cscaMatch.group(1)
          return self._smscNumber